Bituminous composite reinforced with a filler coated with the reaction product of a bitumen and a chromium complex

ABSTRACT

A filler reinforced composite comprising bitumen as a continuous phase and as reinforcement in the bitumen, fillers which have been coated with a chemically-modified bitumen prepared by reacting a bituminous material with a chromium complex.

This is a division of application Ser. No. 055,738, filed July 9, 1979,now U.S. Pat. No. 4,251,577.

This invention relates to asphalt reinforced materials, and moreparticularly to glass fibers treated with chemically-modified asphaltsto promote compatibility between glass fibers and asphalt in themanufacture of glass fiber-reinforced asphalt systems.

In recent years, increasing attention has been given to the use ofreinforcement of asphalt systems as provided by glass fibers. One of theproblems which has been incurred in integrating glass fibers withasphalt as a reinforcement stems from the fact that glass fibers orfragments of glass have smooth, hydrophilic surface characteristics.Thus, the smooth, hydrophilic surfaces of the glass fibers make itdifficult to establish any bond, either chemical or physical, betweenthe glass fibers and the asphalt system in which the glass fibers aredistributed as reinforcement. In fact, as the highly hydrophiliccharacteristics of the glass fibers are formed, a thin film of moisturewhich serves to destroy any chemical or physical bond which mightotherwise be formed between the glass fiber surfaces and the asphalt.

The problem of establishing a secure bonding relationship between theglass fiber surfaces and the asphalt is not aided by the chemical natureof the asphalt. Asphalt is a cementitious material containingpredominantly bitumens occurring in nature or obtained as a result ofthe refining of petroleum. Chemically, the asphalt is made up ofcondensed hydrocarbon rings, and thus is highly hydrophobic in nature,thereby further causing incompatibility with the hydrophilic glass fibersurfaces.

It has been determined that the condensed hydrocarbon ring of asphaltdoes contain various reactive groups, notably carbon-to-carbon doublebonds, carboxy groups and hydroxy groups. These groups, however, do notmeasurably affect the hydrophobic characteristics of asphalt systems. Ithas been proposed, in U.S. Pat. No. 4,036,661, to integrate asphalt withmineral aggregate by adding to the asphalt an organo silicon compound,and preferably one derived from an organo silane in which the organicgroup contains one or more functional groups such as an amino group, anaminoalkyleneamino group, a glycidoxy group, a hydrocarbyl group, anacyloxy group or a mercapto group. The difficulty in the approachdescribed by the foregoing patent stems from the fact that organosilanes of the type taught therein are extremely expensive, and thuslarge quantities would necessarily be used in the construction of anasphalt road containing such silanes. Thus, the procedure proposed iseconomically unattractive.

It is accordingly an object of this invention to provide treated glassfibers for use in the reinforcement of asphalt systems to integrate theglass fibers with the asphalt in an efficient and economical manner.

It is a more specific object of the invention to provide glass fiberswhich have been treated with a chemically-modified asphalt so thatchromium complexes are chemically reacted with the asphalt in such amanner as to establish a chemical bond between the chemically-modifiedasphalt and the glass fiber surfaces.

These and other objects and advantages of the invention will appear morefully hereinafter, and, for purposes of illustration and not oflimitation, an embodiment of the invention is shown in the accompanyingdrawings wherein:

FIG. 1 is a flow diagram-showing the manufacture of continuous glassfibers and their treatment in forming according to the practice of thisinvention;

FIG. 2 is a flow diagram illustrating the treatment of glass fibers inthe form of bundles according to the practice of this invention;

FIG. 3 is a cross sectional view of glass fibers treated in accordancewith the flow diagram of FIG. 1; and,

FIG. 4 is a cross sectional view of a bundle of glass fibers treated inaccordance with the flow diagram of FIG. 2.

The concepts of this invention reside in the treatment of glass fiberswith a chemically-modified bitumen composition to form a coating on theglass fibers, either a thin film coating on the individual glass fiberfilaments and/or a coating in the form of an impregnant of bundles ofglass fibers. The coating of the chemically-modified bitumen is formedof a bitumen which has been reacted with an organic chromium complex,and preferably a complex containing at least one organic group having afunctional group reactive with the asphalt.

The chromium complexes preferred for use in the practice of thisinvention are the well-known Werner complexes formed of a carboxylatogroup coordinated with a nuclear trivalent chromium. Such compounds arethemselves known to the art and are described in U.S. Pat. Nos.2,544,667 and 2,683,156. The preferred Werner complex compounds used inthe practice of this invention are those having the formula: ##STR1##wherein R is the residue of the carboxylato group used to prepare theWerner complex compound.

In the preferred practice of this invention, R is either an alkenylgroup containing 2-10 carbon atoms (e.g., vinyl, allyl, etc.) or asaturated aliphatic or alkyl group containing 1-15 carbon atoms and issubstituted by a functional group which is reactive with the asphalt.Generally, the functional group substituting the alkyl group is an aminogroup, a mercapto group, or a hydroxy group, each of which is reactivewith carboxy groups present in the bitumen. In addition, the alkyl groupcan be substituted with an epoxy group. In that event, the R group hasthe formula: ##STR2## wherein y is an integer ranging from 1 to 5.

The symbol X of the Werner complex compound is halogen, and ispreferably chlorine.

Without limiting the present invention as to theory, it is believed thatthe functional group of the chromium complex becomes chemically bondedto the bitumen, thereby leaving the reactive chromium halide portions ofthe molecule to react with the highly hydrophilic surfaces of theindividual glass fiber filaments to thereby chemically intertie themodified bitumen to the glass surfaces. That effect may be illustratedby reference to the following: ##STR3##

As can be seen from the foregoing equation, a Werner complex, such asthat derived from acrylic acid, is reacted with asphalt at an elevatedtemperature whereby the ethylenic unsaturation of the complex becomeschemically intertied with ethylenic unsaturation contained in theasphalt. The highly acidic chromium atoms remain free to react with theglass fiber surfaces and thereby chemically bond the chemically-modifiedbitumen to the glass fiber surfaces.

When use is made of a Werner complex compound in which R is an alkylgroup substituted with a functional group as described above, a similartype reaction occurs whereby the reactive functional group becomeschemically bonded to the carboxyl groups present in the bitumen.

It has been found that glass fibers treated in that manner canthereafter be employed as reinforcement for bitumens such as asphalt ina variety of applications, including road paving applications, roofingapplications and the like. Thus, it is necessary to use only sufficientquantities of the expensive organo silanes to chemically modify thebitumens applied as a coating to the glass fibers. The bitumen coatingon the glass fibers, in turn, can be securely integrated with bitumensor bitumens and aggregate whereby the chemically-modified bitumencoating on the glass fibers serve to securely intertie the glass fibersurfaces to the bitumen in which the glass fibers are distributed.

The concepts of this invention are not limited to use with glass fibers.In general, the concepts of this invention can be used in the treatmentof natural or synthetic hydrophilic fillers and/or reinforcements inwhich the filler and/or reinforcement is present in the form of discreteparticles. Included are fibers formed of such natural and syntheticssuch as polyvinyl alcohol, cellulose, as well as filler materials suchas glass flake.

The use of the concepts of the present invention with glass flakerepresents a particularly desirable embodiment of the invention. Thus,glass flake, discrete glass platelets can be admixed with thechemically-modified bitumens such as the chemically-modified asphalt inaccordance with the concepts of this invention and then used in roadpaving and roofing applications. The glass flake tends to migrate withinthe asphalt to form a barrier layer of overlapping glass platelets,which in turn serves as a moisture-impervious membrane. This concept canbe particularly advantageous when applied to road paving applicationssince the glass flake membrane serves to prevent moisture frompermeating the asphalt road bed. The result is that there is lessmoisture under the surface of the asphalt to cause damage to the asphaltroad bed through freezing.

The reaction between chemically-modified asphalt and the functionalchromium complexes as described above is preferably carried out bydispersing the asphalt in an aromatic solvent inert under the reactionconditions (i.e., benzene, toluene, xylene, etc.) and then adding thecomplex. Best results are usually achieved when the reaction is carriedout at a temperature ranging from 70° to 200° C. Proportions between thecomplex and the asphalt are not critical and can be varied withinrelatively wide limits. In general, it is preferred that the amount ofthe chromium complex be an amount within the range of 0.001 to 5% byweight based upon the weight of the asphalt.

As indicated, the chemically-modified asphalt compositions can beapplied as a coating to the individual glass fiber filaments, preferablyas they are formed. Referring now to FIG. 1, there is shown a schematicflow diagram illustrating the treatment of glass fibers in accordancewith one embodiment of the invention. As shown in this figure, glass ismelted in a furnace 10 having a bushing 12 on its bottom side. Thebushing is provided with a plurality of openings extending therethroughand the molten glass flows gravitationally through the small openings toform streams 14 which are rapidly attenuated to form fine glassfilaments 16 by winding the filaments about a rapidly rotating drum 20.

The filaments 16 may be coated as they are formed with thechemically-modified asphalt composition, preferably dissolved in asolvent, as they are gathered to form a strand 18. For this purpose, usecan be made of an applicator 22, illustrated as a wiping pad constantlywet with the chemically-modified asphalt treating composition.

The resulting strand is shown in FIG. 3 of the drawing, where it isillustrated that the individual glass fiber filaments 16 contain thechemically-modified asphalt composition as a thin film coating 24 on theindividual surfaces of the glass fiber filaments. The coated glassfibers can be used directly as reinforcement for asphalt or asphalt plusaggregate in accordance with a known manner. The coated glass fibers arethus distributed as reinforcement in asphalt alone or asphalt blendedwith aggregate. The asphalt or asphalt plus aggregate thus serves as acontinuous phase within which the glass fibers coated with thechemically-modified asphalt are distributed. The amount of thechemically-modified asphalt applied as a coating can vary within widelimits. Generally, the coating is applied to the individual glass fibersurfaces in an amount sufficient to constitute from 0.1 to 40% by weightof the weight of the glass fibers.

Alternatively, the glass fibers can be formed into yarns, strands,cords, woven and non-woven fabrics, etc., known in the art as bundles,and then subjected to impregnation. For this purpose, use can be made ofuntreated glass fibers or glass fibers which have been sized with any ofa variety of well-known size compositions. As is well known to thoseskilled in the art, it is frequently the practice, in the processing ofglass fibers in the form of bundles, to employ glass fibers which havebeen sized whereby the size composition imparts lubricity of theindividual glass fiber filaments without destroying their fibrouscharacteristics. In that manner, the glass fibers can be processed inbundle form without risk of destruction of the glass fibers throughmutual abrasion.

In accordance with this embodiment of the invention, a glass fiberbundle is impregnated with the chemically-modified asphalt compositionwhereby the impregnant serves to coat the individual glass fiberfilaments and to completely fill the interstices between the glass fiberfilaments forming the bundle and thereby define a unitary bundlestructure. Apparatus for that purpose is illustrated in FIG. 2 of thedrawings wherein the glass fiber bundle is advanced over a guide roller34 for passage downwardly into a bath 35 containing thechemically-modified asphalt composition. Once in the bath, the bundle isturned under a pair of rollers 36 to effect a sharp bend in the bundlewhich operates to open the bundle and to facilitate more completepenetration of the chemically-modified asphalt composition into thebundle.

The impregnated bundle is then raised from the bath 35 for passagethrough a roller or die 38, operating to remove excess impregnatingcomposition from the bundle. Thereafter, the bundle is advanced over aroller 39 into a drying oven 40 to set the chemically-modified asphaltcomposition in situ in the glass fiber bundle.

The resulting bundle is shown in FIG. 4 of the drawing, and comprises aplurality of glass fibers 16 having the optional thin size coating 34 onthe surfaces thereof and the impregnant 42 in the bundle. As can be seenfrom this figure, the impregnant 42 substantially completely fills theinterstices between the glass fibers and serves to separate theindividual glass fibers each from the other. The resulting bundle canthen be used in reinforcement of asphalt or asphalt plus aggregate asdescribed above whereby the bundles of glass fibers which have beenimpregnated with the chemically-modified asphalt composition aredistributed through the asphalt or asphalt plus aggregate asreinforcement in the continuous phase defined by the latter.

When the chemically-modified asphalt is applied as an impregnant inaccordance with this embodiment of the invention, the amount of thechemically-modified asphalt applied as an impregnant can vary withinrelatively wide limits. Generally, the chemically-modified asphaltimpregnant constitutes from 10 to about 60% by weight based on theweight of the glass fiber bundles. As will be appreciated by thoseskilled in the art, it is also possible to treat the glass fibers twice,first by applying a thin film coating 16 containing thechemically-modified asphalt and then subject bundles of the thus coatedfibers to impregnation whereby the chemically-modified asphalt serves asa size and as an impregnant.

When the concepts of this invention are applied to the use of glassflake, the asphalt, either in a molten or emulsified form, can beblended with the glass flake, and then the resulting composite appliedto a, for example, road bed to form a wear layer. The platelets formingthe glass flake tend to float in the fluid asphalt so as to form anoverlapping, moisture-imprevious layer just beneath the surface. It isthat layer which thus forms a barrier against moisture.

The amount of the glass flake employed is not critical and can be variedwithin relatively wide limits. It is generally preferred that the amountof glass flake employed be such that it forms at least a single layer ofglass flake particles overlapping the adjacent portion to form amoisture-impervious barrier. Best results are usually obtained when theglass flake ranges from 0.001 to 10% by weight based upon the weight ofthe glass flake with which the asphalt is combined.

Having described the basic concepts of the present invention, referenceis now made to the following examples, which are provided by way ofillustration and not by way of limitation, of the practice of thisinvention in the preparation of asphalt compositions chemically modifiedwith organo silicon compounds and their use in the reinforcement ofasphalt systems.

EXAMPLE 1

This example illustrates the preparation of a modified asphaltcomposition useful in the practice of this invention.

A solution of 200 parts by weight of a paving grade asphalt (50/60penetration at 77° F.) is dissolved in 50 parts by weight of toluene andplaced in a stirred flask equipped with a heater. Thereafter, 1.2 partsby weight of acrylato chromic chloride, prepared from acrylic acid andchromyl chloride, are added to the solution.

The solution is then heated to reflux for 3 hours. At the end of thattime, the heating is discontinued and the toluene solvent removed.

The chemically-modified asphalt is then applied as a thin film coatingto glass fibers using the procedure illustrated in FIG. 1 of thedrawing. The chemically-modified asphalt, dissolved in toluene, isapplied to constitute a coating of about 0.85% by weight based on theweight of the glass fibers. It is then combined with asphalt andaggregate as reinforcement. The treated glass fibers are found to havegood adhesion to the asphalt constituting the continuous phase in whichthe glass fibers are distributed as reinforcement.

EXAMPLE 2

Using the procedure described in Example 1, β-alanine chromic chloride,prepared from β-alanine and chromyl chloride, is reated with asphalt inthe presence of a solvent. The chemically-modified asphalt is thereafterapplied as a thin film coating to individual glass fiber filaments usingthe procedure described in FIG. 1.

It is found that good adhesion between the treated glass fibers andasphalt is achieved.

EXAMPLE 3

Using the procedure described in Example 1, the paving grade asphaltdescribed in Example 1 is reacted with 1% by weight of the chromiumcomplex described in Example 2.

The resulting chemically-modified asphalt composition is then employedas a hot melt to impregnate bundles of glass fibers which have beensized with a glass fiber size composition of the type described in U.S.Pat. No. 3,837,989, the disclosure of which is incorporated herein byreference. The impregnant of the modified asphalt is applied in anamount to constitute about 17.5% by weight based on the weight of theglass fiber bundle.

The impregnated bundles are then combined with asphalt and aggregatewhereby the impregnated bundles are distributed through the asphalt andaggregate as a continuous phase, the bundle serving as an impregnanttherefor. Good adhesion between the impregnated bundles of glass fibersand the asphalt is achieved.

EXAMPLE 4

Using the procedure described in Example 1, blown asphalt is reactedwith 0.9% by weight of methacrylato chromic chloride. The resultingchemically-modified asphalt composition can be applied to glass fibersas a thin film coating described in Example 1 or as an impregnant asdescribed in Example 3. In either case, the resulting coated glassfibers are characterized by good adhesion to asphalt or asphalt plus afiller aggregate material.

The procedure employed in Example 4 illustrates another variation in thepractice of this invention. The bitumen employed in that example isblown asphalt, asphalt which has been modified by reaction with air. Asis now known to those skilled in the art, blown asphalt is partiallyoxidized to thereby increase the content of carboxyl groups in thebitumen itself. Conventional blown asphalt can be used in the practiceof this invention, and is prepared by passing an oxygen-containing gas(preferably air) through the asphalt, while the asphalt is maintained atan elevated temperature within the range of 80° to 300° C., either withor without a solvent. It is generally preferred that the blown asphalthave an oxygen content ranging from 1-10% by weight based upon theweight of the asphalt.

It will be understood that various changes and modifications can be madein the details of procedure, formulation and use, without departing fromthe spirit of the invention, especially as defined in the followingclaims.

We claim:
 1. A reinforced composite comprising a bitumen as a continuous phase and, as reinforcement in the bitumen, a filler selected from the group consisting of natural and synthetic fillers having a coating thereon, said coating consisting essentially of the reaction product of (a) bitumen and (b) a chromic complex containing a carboxylato group containing a functional group reactive with the bitumen.
 2. A composite as defined in claim 1 wherein said fillers are hydrophilic fillers.
 3. A composite as defined in claim 1 wherein the filler is in the form of fibers. 